The present invention relates to a technique regarding a printing plate material having a plastic sheet support for computer to plate (hereinafter also referred to as CTP) system, and particular to a printing plate material, a printing plate material roll, a printing plate manufacturing process and a printing process which are controlled during printing by a wireless tag.
The CTP system, in which image data can be directly recorded in a printing plate material, has been widely used accompanied with the digitization of printing data. As a printing plate material usable for CTP, there are a printing plate material comprising an aluminum support such as a conventional PS plate, and a flexible printing plate material comprising a flexible resin film sheet and provided thereon, various functional layers. Recently, in the commercial printing industries, there is a tendency that many kinds of prints are printed in a small amount, and an inexpensive printing plate material with high quality has been required in the market.
As a conventional flexible printing plate material, there are a silver salt diffusion transfer type printing plate material as disclosed in Japanese Patent O.P.I. Publication No. 5-66564, in which a silver salt diffusion transfer type light sensitive layer is provided on a flexible sheet; an ablation type printing plate material as disclosed in Japanese Patent O.P.I. Publication Nos. 8-507727, 6-186750, 6-199064, 7-314934, 10-58636 and 10-244773 in which a hydrophilic layer and a lipophilic layer, one of which is the outermost layer, are provided on a flexible sheet where the outermost layer is ablated by laser exposure to prepare a printing plate; and a heat melt type printing plate material in which a hydrophilic layer and a heat melt image formation layer are provided on a flexible sheet where a hydrophilic layer or a heat melt image formation layer is imagewise heated by laser exposure to heat-fix the image formation layer onto the hydrophilic layer (see for example, Patent document 1 below).
The silver salt diffusion transfer type printing plate material requires a wet development step and a-drying step after exposure, which does not give sufficient dimensional accuracy during the image formation step, and is not suitable to obtain printed matter with high image-quality.
The ablation type printing plate material does not require a wet development step, but image formation due to ablation is likely to fluctuate in dot shape. Further, there is problem in which the interior of the exposing apparatus or the printing plate surface is contaminated by scattered matters caused by ablation of the layer.
A process, comprising a step of forming on a hydrophilic layer a heat-melted image, heated by conversion from laser light, is suitable to obtain high precision images. Among types of this process, there is a so-called on-press development process in which when a printing plate material after image writing is mounted on an off-set press, and a dampening solution is supplied to the printing plate material during printing, only the image formation layer at non-image portions is swollen or dissolved by the dampening solution, and transferred to a printing paper (paper waste), whereby the image formation layer at non-image portions is removed. This process does not require a special development after exposure, resulting in excellent stability of printing quality and excellently meeting environmental concern.
In general, in the CTP system a dot image with a screen line number of 100 to 300 is recorded employing laser beams with a beam spot diameter condensed to from 5 to 30 μm, and each dot is recorded by plural laser beams. Therefore, theoritically, tone reproduction can be optionally varied by varying exposure pattern due to the laser or output power of the laser. In a conventional CTP printing, conditions of a plate making apparatus have been initialized in order to obtain intended prints.
However, it is necessary to provide a different plate making apparatus or to change plate making conditions, due to kinds or size of printing plate materials. Therefore, when various kinds or sizes of printing plate materials are used, plate making conditions to meet each of their kinds or sizes need to be manually changed in the plate making apparatus used or a plate making apparatus exclusive to each of their kinds or sizes are required.
Further, also in printing employing a printing plate material for CTP, optimum printing conditions are different due to kinds of printing materials such as kinds of printing ink, a dampening solution, printing paper as well as kinds of printing plate materials and image patterns, an operator is required to set printing conditions optimum for each of the printing plate materials, individually.
Since exposure conditions or a balance between a dampening solution and printing ink have a great influence on on-press developability particular in an on-press development type printing plate material, an optimum printing condition is required to be set in order to keep printing quality constant.
However, even if an optimum printing condition is set, individually, some fluctuation of printing quality cannot be prevented on account of product lot change, aging change of printing performance, change of printing performance due to ambient atmosphere such as temperature and humidity, output power change of a light source for exposure, or change of printing conditions.
Generally, printing plate materials of various sizes need to be supplied so as to meet various printing presses used. However, when a printing plate material stock roll is manufactured, the size of the printing plate material manufactured is determined by manufacturing facilities.
The manufactured printing plate material stock roll may comprise quality defects or manufacture faults. Therefore, in order to obtain printing plate materials of plural sizes from a printing plate material stock roll with a specific size, the stock roll must be manufactured to minimize printing plate material waste. Hitherto, manual control is carried out based on dimension information or fault information, which are recorded on paper attached to a printing plate material stock roll, which requires many procedures and is likely to cause errors.
In recent years, in a field such as contactless IC cards, RFID (wireless tag) has been developed. As a wireless tag of low price and compact size is developed, it has been used not only as a card with high added value but as a tool for production control or inventory control of products (see for example Patent document 2 below).
[Patent Document 1]
    Japanese Patent O.P.I. Publication No. 2001-96710[Patent Document 2]    Japanese Patent O.P.I. Publication No. 2003-67883